Hall effect sensors and structures are used in a variety of systems to measure magnetic field. Hall effect structures make use of the Hall effect, whereby a voltage is generated across a conductor or semiconductor due to Lorentz forces on moving charge carriers. This voltage, called the Hall voltage, can be measured to ascertain the strength of the applied magnetic field. The Hall voltage is inversely proportional to the density of charge carriers. Accordingly, Hall effect structures and sensors are often made of a semiconducting material with relatively lower charge carrier density than typical conductors.
Hall effect sensors can be either vertically or horizontally oriented in a semiconductor die. Vertical Hall effect structures respond to a magnetic field component parallel to the main surface of a die in which they are positioned, and into which they extend.
Four-contact and three-contact Hall devices are known in the art. In a four-contact device, electrical supply terminals are connected to a first contact and a second contact (referred to as supply contacts) that can be positioned along a primary axis in some systems. Third and fourth contacts (referred to as output contacts) are positioned to measure the voltage generated by the current flow. The output contacts can be positioned along the secondary axis in some systems. In a three-contact Hall device, two contacts can be used for electrical supply and a third can be used to measure signal. For example, two supply contacts can be used to provide a current input, and an output voltage can be measured at the third contact (the output contact). Alternatively, all of the contacts can be used as supply contacts, and the output voltage can be measured between two of the contacts. In yet another operating phase, first and second supply contacts can provide voltage input, and the output voltage can be measured between two output contacts.
Permutation of the supply and output contacts is referred to as spinning During spinning, equal current or voltage is provided to the system in all operating phases. Vertical Hall devices often have different internal resistance in various operating phases, and so the input voltage is different in each phase. This is a disadvantage, because voltage “headroom” must be provided in the circuit (i.e., the circuit must be capable of providing sufficient current or voltage supply across every Hall device in every operating phase that is sufficient to pass through the Hall device having the largest resistance) and power can be unnecessarily and inhomogeneously dissipated in a system having unequal resistance in the various operating phases. This can lead to increased offset or zero-point errors due to temperature gradients between the output contacts of the vertical Hall devices and associated thermal electromotive force.